1. Field of the Invention
The present invention relates generally to the field of optical devices, and particularly a variable optical attenuator.
2. Description of Related Art
Fiber optics transmission is now a common platform for transporting voice, data, and images. As the demand for data carrying capacity continues to increase, optical companies are finding techniques to utilize the bandwidth of existing fiber-optic cable more efficiently. An established technique for increasing the carrying capacity of existing fiber cable is Wavelength Division Multiplexing (WDM) in which multiple information channels are independently transmitted over the same fiber using multiple wavelengths of light. In this practice, each light-wave-propagated information channel corresponds to light within a specific wavelength range or xe2x80x9cbandxe2x80x9d.
Due to the increase network traffic resulting from the use of the WDM technique, companies are designing sophisticated optical switching devices which can quickly route numerous channels among various optical communications lines. In these instances, the optical power level of each added or dropped channel has to be controlled. Conventional solutions for optical switching devices use an electronically-controlled variable optical attenuator (VOA) to adjust the power level of optical beam, or use an attenuation filter to block portion of beams via step motor, or use microelectromechanical mirrors. A principle shortcoming in a conventional solution is the cost in designing an electronically controlled VOA. Accordingly, the present invention addresses these needs.
The present invention discloses an optical variable attenuator having a reflector in a first position, and a mechanical device for positioning the reflector from the first position to a second position. The optical variable mechanical device comprises a first and second guide slots, a moving part, and a screw, where a first guide slot is placed parallel to the second guide slot. The moving part is placed in between and extending in the parallel direction to the first and second guide slots, the screw extending into and away from the moving part.
Optionally, a first and second spring loaded lock pins are used to mount a moving part to avoid injecting any tip and tilt errors. The lock pins are guided by two machined slots on a main body of a variable optical attenuator. Alternatively, the two guide slots can be replaced with a pair of precision pins mounted side-by-side. Advantageously, the present invention significantly simplifies the complexity in the adjustment of a variable optical attenuator.
Other structures and methods are disclosed in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims.